Dormant Company - even with bank movements?

If a non-trading (dormant from birth) company has movements in/out of it's bank account that zero out and are all balanced by movements on the inter-company account with a related company (same owner, same director) and no income (including interest) or expenses of any kind such that it has nothing to record on the profit & loss account or on the balance sheet at year end, then

1. Is this company dormant?

2. If the (small company, abbreviated) accounts are simple to prepare (in this case, mostly zero entries) what is the advantage of being a dormant company? What are the ramifications of being non-dormant and therefore trading, but with no revenue and no costs and no assets and no liabilities?

3. Are there HMRC rules/guidelines governing the use and recording of an inter-company account (I assume that this is treated like a phantom bank account in the accounts of each company)